Double-Sided Adhesive Tape Having Improved Impact Strength for Display Device

ABSTRACT

The present disclosure relates generally to a double-sided adhesive tape having improved impact strength for a display device. More particularly, the double-sided adhesive tape includes a base layer, a foam adhesive layer formed on one surface of the base layer and made of acrylic foam, and an adhesive layer formed on the other surface of the base layer. The double-sided adhesive tape having improved impact strength for the display device having the above structure in which the foam adhesive layer having excellent impact strength is formed, thereby suppressing occurrence of cracking on a glass surface of the display device due to external impacts and exhibiting an excellent waterproofing effect.

TECHNICAL FIELD

The present disclosure relates generally to a tape having impactstrength for a display device. More particularly, the present disclosurerelates to a double-sided adhesive tape having improved impact strengthfor a display device, in which the double-sided adhesive tape includes afoam adhesive layer having excellent impact strength, therebysuppressing occurrence of cracking on a glass surface of the displaydevice due to external impacts and exhibiting an excellent waterproofingeffect.

BACKGROUND ART

In general, double-sided adhesive tapes are used in display devices tobond and fix various types of display panels, electronic components, andthe like. A double-sided adhesive tape may be interposed between adisplay window and a display assembly to serve to bond the same. Asdescribed above, the double-sided adhesive tape can serve to preventintrusion of external impurities while fixing the edge of a display andalso can prevent light emitted from a light source mounted on a rearside of a liquid crystal panel or the like from leaking from the edge ofthe display.

Conventionally, a double-sided adhesive tape is formed by punching thetape in a shape of a picture frame or the like and is used to bedisposed around a display screen. In recent years, with the trend towardminiaturization of electronic devices and use of a large display screen,the area of an opening of the display screen has been increased, and duethereto, a bonding fixing portion around the display screen has becomenarrower. For this reason, the adhesive tape is decreasing in adhesivearea year by year, and as the adhesive area becomes narrower, furtherexcellent adhesive performance is required.

In addition, with the trend toward thin portable electronic devices suchas smartphones and digital cameras in recent years, the double-sidedadhesive tape has become thinner. Also, as consumer demand forwaterproof performance of portable electronic devices increases inaddition to adhesive performance, development of double-sided adhesivetapes with waterproof performance is required to secure a competitiveadvantage in the market.

In addition, the trend toward thin portable electronic devices such assmartphones and digital cameras in recent years has also lead tothinning of a glass surface of a display device, and due thereto, theincidence of cracking on the glass surface of the display device due toexternal impacts may be increased Therefore, recently, in order toprevent cracking of the glass surface of the display device fromoccurring due to external impacts, a double-sided adhesive tape to whicha foam layer having excellent impact strength is applied between a baselayer and an adhesive layer has been manufactured.

However, in the case of the double-sided adhesive tape to which the foamlayer is applied between the base layer and the adhesive layer asdescribed above, the adhesive layer and the foam layer have to be formedseparately, and thus there is a problem in that a manufacturing processmay be complicated and manufacturing cost may be excessively increased.

DISCLOSURE Technical Problem

Accordingly, the present invention has been made keeping in mind theabove problems occurring in the related art, and the present inventionprovides a double-sided adhesive tape having improved impact strengthfor a display device, in which the double-sided adhesive tape includes afoam adhesive layer having excellent impact strength, therebysuppressing occurrence of cracking on a glass surface of the displaydevice due to external impacts.

Technical Solution

According to one aspect of the present disclosure, there is provided adouble-sided adhesive tape having improved impact strength for a displaydevice, the double-sided adhesive tape including: a base layer; a foamadhesive layer formed on one surface of the base layer and made of anacrylic foam; and an adhesive layer formed on the other surface of thebase layer.

According to another aspect of the present disclosure, there is provideda double-sided adhesive tape having improved impact strength for adisplay device, the double-sided adhesive tape including: a base layer;and a foam adhesive layer formed on each of opposite surfaces of thebase layer and made of acrylic foam.

Preferably, the base layer may have a thickness of 12 to 150 micrometersand may be made of one selected from among the group consisting ofpolyethylene terephthalate, polyurethane, polyethylene naphthalate, andpolyimide.

More preferably, the foam adhesive layer may have a thickness of 25 to150 micrometers.

More preferably, the foam adhesive layer may include 100 parts by weightof an acrylic mixture, 0.01 to 5.0 parts by weight of a foaming agent,0.01 to 2.0 parts by weight of a curing agent, and 90 to 110 parts byweight of a solvent.

Still more preferably, the acrylic mixture may include 100 parts byweight of normal butyl acrylate, 80 to 100 parts by weight of2-ethylhexyl acrylate, and 1 to 12 parts by weight of acrylic acid.

Advantageous Effects

The double-sided adhesive tape having improved impact strength for thedisplay device as described above includes the foam adhesive layerhaving excellent impact strength. Therefore, it is possible to suppressoccurrence of cracking on the glass surface of the display device due toexternal impacts and can exhibit an excellent waterproofing effect.

DESCRIPTION OF DRAWINGS

FIG. 1 is an exploded perspective view illustrating a double-sidedadhesive tape having improved impact strength for a display deviceaccording to an embodiment of the present disclosure.

FIG. 2 is an exploded perspective view illustrating a double-sidedadhesive tape having improved impact strength for a display deviceaccording to another embodiment of the present disclosure.

MODE FOR INVENTION

Hereinafter, exemplary embodiments of the present invention and thephysical properties of each component will be described in detail.However, these embodiments are only intended to describe the presentinvention in detail such that those of ordinary skill in the art towhich the present invention belongs can easily carry out the inventionand the technical idea and scope of the present invention are notlimited by them.

A double-sided adhesive tape having improved impact strength for adisplay device disclosed herein includes a base layer 10, a foamadhesive layer 20 formed on one surface of the base layer 10 and made ofacrylic foam, and an adhesive layer 30 formed on the other surface ofthe base layer 10.

In addition, the double-sided adhesive tape having improved impactstrength for the display device disclosed herein may be used in a formin which the adhesive layer 30 is replaced with the foam adhesive layer20 and thus foam adhesive layers 20 are formed on opposite surfaces ofthe base layer 10.

The base layer 10 is a layer serving as a base material of thedouble-sided adhesive tape having improved impact strength for thedisplay device disclosed herein and has a thickness of 12 to 150micrometers. The base layer imparts a predetermined shape to thedouble-sided adhesive tape having improved impact strength for thedisplay device disclosed herein and serves to prevent deformation of thedouble-sided adhesive tape due to external impacts and impart waterproofperformance thereto.

When the thickness of the base layer 10 is less than 12 micrometers, thedouble-sided adhesive tape may be easily deformed or cracked due toexternal impacts or tensile force. On the contrary, when the thicknessof the base layer 10 is greater than 150 micrometers, the thickness ofthe double-sided adhesive tape may be excessively increased, making itunsuitable for electronic devices that are miniaturized and thinned.

In addition, it is preferable that the base layer 10 is made of a resinhaving relatively low cost and excellent mechanical properties, such aspolyethylene terephthalate, polyurethane, polyethylene naphthalate, andpolyimide.

The foam adhesive layer 20 is formed with a thickness of 25 to 150micrometers on one surface of the base layer 10 and made of acrylicfoam. The foam adhesive layer imparts adhesiveness to the double-sidedadhesive tape having improved impact strength for the display devicedisclosed herein, and serves to suppress occurrence of cracking on aglass surface of the display device due to external impacts by improvingimpact strength and to impart a waterproofing effect.

Herein, the foam adhesive layer 20 includes 100 parts by weight of anacrylic mixture, 0.01 to 5.0 parts by weight of a foaming agent, 0.01 to2.0 parts by weight of a curing agent, and 90 to 110 parts by weight ofa solvent. It is preferable that the acrylic mixture has a weightaverage molecular weight of 300000 to 900000 and includes 100 parts byweight of normal butyl acrylates, 80 to 100 parts by weight of2-ethylhexyl acrylates, and 1 to 12 parts by weight of acrylic acid.

In addition, the foaming agent is not particularly limited as long asbeing contained in an amount of 0.01 to 5.0 parts by weight and being acomponent that serves to foam the acrylic mixture to provide a foamadhesive layer 20 exhibiting impact strength, but any one can be used.However, it is preferable to use MSH-320 available from SDI company.

When the amount of the foaming agent is less than 0.01 parts by weight,the foaming efficiency of the foam adhesive layer 20 may be lowered andthus the impact strength may be lowered. On the contrary, when theamount of the foaming agent is greater than 5.0 parts by weight, foamingof the foam adhesive layer 20 may be excessively performed and thusmechanical properties of the foam adhesive layer 20 may be lowered.

In addition, the curing agent is not particularly limited as long asbeing a component that is capable of curing the acrylic mixture, but anyone can be used. However, it is preferable to use isocyanate.

In addition, the solvent is not particularly limited as long as being acomponent that serves to allow the acrylic mixture and the foamingagent, and the curing agent to be uniformly mixed so as to provide afoam adhesive layer 20 exhibiting homogeneous physical properties, butany one can be used. However, it is preferable to use ethyl ketone.

The foam adhesive layer 20 including the above components is formed insuch a manner that the acrylic mixture, foaming agent, the curing agent,and the solvent is mixed, and then a mixture thereof is coated onto onesurface of the base layer 10 by a comma coating method to a thickness of10 to 140 micrometers, while being foamed at a temperature of 170° C. toform a foam adhesive layer having a thickness of 25 to 150 micrometers.When the thickness of the foam adhesive layer 20 is less than 25micrometers, the impact strength of the foam adhesive layer 20 may belowered, and when the thickness of the foam adhesive layer 20 is greaterthan 150 micrometers, mechanical properties thereof may be lowered.

The adhesive layer 30 is formed on the other surface of the base layer10 to a thickness of 25 to 150 micrometers in such a manner that amixture of 100 parts by weight of an acrylic mixture, 0.01 to 2.0 partsby weight of a curing agent, and 90 to 110 parts by weight of a solventis coated onto the other surface of the base layer 10 by a comma coatingmethod to a thickness of 25 to 150 micrometers. The adhesive layerserves to impart adhesion to the double-sided adhesive tape havingimproved impact strength for the display device disclosed herein.

Herein, the critical meaning according to the specific components andamount of the acrylic mixture, the curing agent, and the solvent is thesame as the acrylic mixture, the curing agent, and the solvent used inthe foam adhesive layer 20, and thus a detailed description thereof willbe omitted.

When the thickness of the adhesive layer 30 is less than 25 micrometers,the adhesive performance and impact strength may be lowered. On thecontrary, when the thickness of the adhesive layer 30 is greater than150 micrometers, the adhesive performance may not be significantlyimproved, but the thickness of the double-sided adhesive tape may beexcessively increased, making it unsuitable for electronic devices thatare miniaturized and thinned.

Hereinafter, a method of manufacturing a double-sided adhesive tapehaving improved impact strength for a display device disclosed herein,and the physical properties of a double-side tape manufactured therebywill be described with reference to examples.

Example 1

A double-sided adhesive tape having improved impact strength for adisplay device was manufactured by a process in which: a base layer wasformed of a 50 micron thick polyethylene terephthalate film; a mixtureof 100 parts by weight of an acrylic mixture (prepared by polymerizing100 parts by weight of normal butyl acrylate, 90 parts by weight of2-ethylhexyl acrylate, and 10 parts by weight of acrylic acid, andhaving a weight average molecular weight of 700,000), 1 part by weightof a foaming agent (MSH-320 available from SDI company), 1 part byweight of a curing agent (isocyanate), and 100 parts by weight of asolvent (methylethyl ketone) was coated onto one surface of the baselayer by a comma coating method to a thickness of 90 micrometers, whilebeing foamed at a temperature of 170° C. to form a foam adhesive layerhaving a thickness of 100 micrometers; and a mixture of 100 parts byweight of an acrylic mixture (prepared by mixing 100 parts by weight ofnormal butyl acrylate, 90 parts by weight of 2-ethylhexyl acrylate, and10 parts by weight of acrylic acid, and having a weight averagemolecular weight of 700,000), 1 part by weight of a curing agent(isocyanate), and 100 parts by weight of a solvent (methylethyl ketone)was coated onto the other surfaces of the base layer by a comma coatingmethod to a thickness of 100 micrometers to form an adhesive layer.

Example 2

A double-sided adhesive tape having improved impact strength for adisplay device was manufactured by a process in which: a base layer wasformed of a 50 micron thick polyethylene terephthalate film; and amixture of 100 parts by weight of an acrylic mixture (prepared bypolymerizing 100 parts by weight of normal butyl acrylate, 90 parts byweight of 2-ethylhexyl acrylate, and 10 parts by weight of acrylic acid,and having a weight average molecular weight of 700,000), 1 part byweight of a foaming agent (MSH-320 available from SDI company), 1 partby weight of a curing agent (isocyanate), and 100 parts by weight of asolvent (methylethyl ketone) was coated onto each of opposite surfacesof the base layer by a comma coating method to a thickness of 90micrometers, while being foamed at a temperature of 170° C. to form foamadhesive layers each of which has a thickness of 100 micrometers.

Comparative Example 1

A double-sided adhesive tape having improved impact strength for adisplay device was manufactured by a process in which: a base layer wasformed of a 50 micron thick polyethylene terephthalate film; a mixtureof 100 parts by weight of a urethane resin (prepared by polymerizing 70parts by weight of polytetramethylene ether glycol and 30 parts byweight of isophorone diisocyanate, and having a weight average molecularweight of 110,000), 100 parts by weight of a solvent (methylethylketone), 1 part by weight of a foaming agent (MSH-320 available from SDIcompany), and 1 part by weight of a curing agent (isocyanate) was coatedonto one surface of the base layer by a comma coating method to athickness of 40 micrometers and dried at 100° C. to remove the solventcomponent; a coating layer from which the solvent component was removedwas foamed at 170° C. to form a foam layer having a thickness of 50 μm;and a mixture of 100 parts by weight of an acrylic resin (prepared bypolymerizing 50 parts by weight of normal butyl acrylate, 45 parts byweight of 2-ethylhexyl acrylate, and 5 parts by weight of acrylic acid,and having a weight average molecular weight of 700000), 1 part byweight of a curing agent (isocyanate), and 100 parts by weight of asolvent (methylethyl ketone) was coated on each of upper and lowersurfaces of the base layer on which the foam layer is formed by a commacoating method to a thickness of 75 micrometers to form adhesive layers.

Comparative Example 2

A double-sided adhesive tape having improved impact strength for adisplay device was manufactured in the same manner as in the ComparativeExample 1, except that a foam layer using an acrylic resin was furtherformed on a lower surface of a base layer and adhesive layers having athickness of 50 micrometers were formed on an upper surface and thelower surface of the base layer.

Comparative Example 3

A double-sided adhesive tape having improved impact strength for adisplay device was manufactured in the same manner as in the ComparativeExample 2, except that a foam adhesive layer as in the Example 1 wasformed on one surface of a base layer to a thickness of 50 micrometersand an adhesive layer as formed on a lower surface of the base layer inthe Comparative Example 2 was formed to a thickness of 50 micrometers.

Comparative Example 4

A double-sided adhesive tape having improved impact strength for adisplay device was manufactured in the same manner as in the ComparativeExample 3, except that a foam adhesive layer as in the Example 1 wasalso formed on the other surface of a base layer.

Comparative Example 5

A double-sided adhesive tape having improved impact strength for adisplay device was manufactured in the same manner as in the Example 1,except that a foam adhesive layer formed on one surface of a base layerwas replaced with an adhesive layer.

Comparative Example 6

A double-sided adhesive tape having improved impact strength for adisplay device was manufactured by a process in which a foam adhesivelayer as in the Example 1 was formed to a thickness of 50 micrometers toform a base layer, and an adhesive layer as in the Example 1 was formedon each of opposite surfaces of the base layer.

After applying the double-sided adhesive tape having improved impactstrength for the display device manufactured through each of theExamples 1 to 2 and the Comparative Examples 1 to 6 to a display's glasssurface, physical properties thereof were measured and shown in Table 1below.

(However, the physical properties is composed of prevention of breakageof the display's glass surface, reworkability and residue evaluation,and waterproof performance evaluation)

The effect of preventing breakage of the display's glass surface wasmeasured using a method of measuring the number of times the display'sglass surface was broken by placing a steel plate and an SUS plate on animpact measuring sensor, sampling each of the double-sided adhesivetapes manufactured in Examples 1 to 2 and Comparative Examples 1 to 6 toprepare samples having a thickness of 100 μm and a size of 10 cm inwidth×10 cm in length, and attaching one surface of each of the samplesto the display's glass surface (tempered glass) and attaching other sideto the surface of the SUS plate, and dropping 16 g and 30 g steel ballsat a 100 cm height.

In addition, in the reworkability and residue evaluation, reworkabilitywas measured using a method of cutting each of the double-sided adhesivetapes manufactured in Examples 1 to 2 and Comparative Examples 1 to 6into a size of 25 mm in width×150 mm in length and attaching each of cutdouble-sided adhesive tapes to a display's glass surface (temperedglass) having a size of 70 mm in width×200 mm in length, and when thedouble-sided adhesive tape was removed from the display's glass surfaceafter 72 hours at room temperature, marking as “OK” when thedouble-sided adhesive tape was removed without breaking and marking as“NG” when breakage occurred. The residue was measured using a method ofvisually observing the display's glass surface after the above process,and when an adhesive remained on the glass surface, marking as residuepresence.

In addition, the waterproof performance was measured using a method ofcutting of each of the double-sided adhesive tapes manufactured inExamples 1 to 2 and Comparative Examples 1 to 6 to a size of 48 mm inwidth×48 mm in length then cutting the inside of each of cutdouble-sided adhesive tapes into a size of 47.3 mm in width×47.3 mm inlength to prepare square frame-shaped samples having a frame width of0.7 mm, attaching each of the samples onto a polycarbonate (PC) platehaving the same size as a magnesium (Mg) plate in 60 mm in width×60 mmin length×6.5 mm in thickness, and attaching a glass plate in 50 mm inwidth×50 mm in length×2.8 mm in thickness. The prepared samples wereleft at 24° C. for 72 hours and then placed in a water tank filled with2 m of water, and after 144 hours, the samples were collected tovisually check for leakage. Leak-free samples were marked Pass andleaked samples were marked NG.

TABLE 1 Comparative Comparative Comparative Comparative ComparativeComparative Classification Example 1 Example 2 example 1 example 2example 3 example 4 example 5 example 6 Drop impact 16 g 4 5 4 4 5 5 1 2glass breakage 30 g 3 3 2 3 3 4 1 1 prevention (Count) Reworkability OKOK OK OK OK OK OK NG Residue None None None None None None None PresenceWaterproof Pass Pass Pass Pass Pass Pass Pass Pass (IPX 8)

As illustrated in Table 1 above, it can be seen that the double-sidedadhesive tapes having improved impact strength for the display devicesmanufactured through the Examples 1 to 2 have excellent physicalproperties such as a glass breakage prevention effect, reworkability,reduced residue, and waterproof performance when compared to thedouble-sided adhesive tapes having improved impact strength for thedisplay devices manufactured through Comparative Examples 1 to 6.

DESCRIPTION OF THE REFERENCE NUMERALS IN THE DRAWINGS

-   -   10; base layer    -   20; foam adhesive layer    -   30; adhesive layer

INDUSTRIAL APPLICABILITY

The present invention can be used as a double-sided adhesive tape forbonding and fixing display panels, electronic components, and the liketo protect displays and electronic products against impacts.

1. A double-sided adhesive tape having improved impact strength for adisplay device, the double-sided adhesive tape comprising: a base layer;a foam adhesive layer formed on one surface of the base layer and madeof an acrylic foam; and an adhesive layer formed on the other surface ofthe base layer.
 2. A double-sided adhesive tape having improved impactstrength for a display device, the double-sided adhesive tapecomprising: a base layer; and a foam adhesive layer formed on each ofopposite surfaces of the base layer and made of acrylic foam.
 3. Thedouble-sided adhesive tape of claim 1, wherein the base layer has athickness of 12 to 150 micrometers and is made of one selected fromamong the group consisting of polyethylene terephthalate, polyurethane,polyethylene naphthalate, and polyimide.
 4. The double-sided adhesivetape of claim 1, wherein the foam adhesive layer has a thickness of 25to 150 micrometers.
 5. The double-sided adhesive tape of claim 1,wherein the foam adhesive layer includes 100 parts by weight of anacrylic mixture, 0.01 to 5.0 parts by weight of a foaming agent, 0.01 to2.0 parts by weight of a curing agent, and 90 to 110 parts by weight ofa solvent.
 6. The double-sided adhesive tape of claim 5, wherein theacrylic mixture includes 100 parts by weight of normal butyl acrylate,80 to 100 parts by weight of 2-ethylhexyl acrylate, and 1 to 12 parts byweight of acrylic acid.
 7. The double-sided adhesive tape of claim 2,wherein the base layer has a thickness of 12 to 150 micrometers and ismade of one selected from among the group consisting of polyethyleneterephthalate, polyurethane, polyethylene naphthalate, and polyimide. 8.The double-sided adhesive tape of claim 2, wherein the foam adhesivelayer has a thickness of 25 to 150 micrometers.
 9. The double-sidedadhesive tape of claim 2, wherein the foam adhesive layer includes 100parts by weight of an acrylic mixture, 0.01 to 5.0 parts by weight of afoaming agent, 0.01 to 2.0 parts by weight of a curing agent, and 90 to110 parts by weight of a solvent.